Method for removing microelectronic circuits from substrates and tool used in removal

ABSTRACT

The method of removing an epoxy bonded microelectronic component from a substrate includes the steps of heating a removal tool comprising a blade portion. The heated blade portion engages against the cured epoxy positioned around the edge of the component, and the epoxy is removed. The blade portion is positioned between an edge of the component and an adjacent portion of the substrate to lift the component from the substrate. A screwdriver receiving tip can also be attached to the removal tool. The screwdriver receiving tip includes an orifice that receives a screwdriver shaft that is freely rotatable therein. The removal tool is heated, thereby heating the screwdriver receiving tip and screwdriver shaft so that any screw to be removed is heated and removed. A tool is also disclosed for removing the microelectronic component from a substrate. The tool includes a removal tool comprising a proximal body and a distal heating end. A screwdriver receiving tip is removably mounted on the distal heating end of the removal tool. The screwdriver receiving tip has an orifice for receiving a screwdriver shaft.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of previously filedProvisional Patent Application, Ser. No. 60/063,163, filed Sept. 30,1997.

FIELD OF THE INVENTION

The present invention relates to electronics manufacturing and repair,and more particularly, to removing microelectronic components, such asintegrated circuits, from substrates on which the microelectroniccomponents are secured.

BACKGROUND OF THE INVENTION

At present, the electronic industry uses hot gas techniques, precisemachining techniques and mechanical removal (chiseling) techniques fornon-destructively removing microelectronic integrated circuits (IC's)and other similar microelectronic components, such as staked fasteners,from substrates following epoxy cure. The microelectronic components areremoved during upgrades, repair and replacement, or substratesubstitution or reuse. In some of the microelectronic component systems,the components have screws (staked fasteners) to aid in securing thecomponent to a substrate. Typically, the screws can be secured by epoxy.The edges of the component can also be bonded by an epoxy, makingremoval difficult because of the epoxy bond. The three removaltechniques mentioned above also have drawbacks.

The use of hot gas may heat the integrated circuit or other similarmicroelectronic component and the substrate to a temperature in excessof 300 C. This could cause damage to the microelectronic component, thusnegating any subsequent use of the component or integrated circuit.Additionally, the excessive temperature could damage other similarlypositioned microelectronic components, and in the worst case scenario,the substrate itself could be severely damaged, causing an expensiveloss of either the substrate or all components mounted on the substrate.

Very precise machining techniques can be exact enough to remove anysurrounding, cured epoxy that secures a microelectronic component to thesubstrate. However, the machining would require, in addition to exactmachining tools and methods, a very precise vacuum wand or draw systemwith sufficient vacuum controls to prevent debris from flying off anddamaging any adjacent microelectronic components or integrated circuits.

Mechanical chiseling is difficult because it requires significant forceto be exerted on a small, exactly machined chiseling blade. The excessforce exacted on the blade to remove the cured epoxy commonly damagesneighboring devices. Mechanical removal techniques also requirerelatively large forces to be exerted against the substrate, which candamage adjacent components and the substrate itself. This would defeatthe purpose of reusing the substrate and associated microelectroniccomponents.

There is, therefore, a need to permit non-destructive integrated circuitand similar microelectronic component removal to permit reuse of thosecomponents. If these microelectronic components could be removedsuccessfully without damaging the components themselves, then thesubstrate could also be reused for other applications. This could createan economic benefit when electronic systems are upgraded, repaired andexchanged.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a methodof removing epoxy bonded integrated circuits and other microelectroniccomponents from a substrate that does not damage the microelectroniccomponent itself, as well as any other adjacent components.

It is still another object of the present invention to provide a methodof removing epoxy bonded integrated circuits and similar microelectroniccomponents from a substrate that does not use machining, hot gas or amechanical chiseling processes.

The present invention is advantageous because it provides a method forremoving an epoxy bonded microelectronic component from a substratewithout using a hot gas, machining or mechanical chiseling process, butallowing microelectronic component removal without excessive damage. Theinvention also provides a unique tool that is adapted for removing themicroelectronic components from the substrate, such as when themicroelectronic component includes screws bonded by epoxy, which aid insecuring the components to the substrate.

In accordance with the present invention, the method comprises the stepsof removing a microelectronic component from a substrate, wherein thecomponent is bonded around the edges thereof by a cured epoxy. Themethod includes the steps of heating a removing tool comprising a bladeportion, engaging the heated blade portion against cured epoxy positionaround the edge of the component, and removing the epoxy. The methodalso comprises positioning the blade portion between an edge of thecomponent and an adjacent portion of the substrate to lift the componentfrom the substrate.

In still another aspect of the present invention, the microelectroniccomponent includes screws bonded by epoxy that aid in securing themicroelectronic component to the substrate. In such a structure, ascrewdriver receiving tip is attached to the removal tool. Thescrewdriver receiving tip includes an orifice for receiving ascrewdriver shaft. The method further comprises the steps of receivingwithin the orifice a screwdriver shaft that is freely rotatable therein,and heating the removal tool and thereby heating the screwdriverreceiving tip and the screwdriver shaft. The method further comprisesheating the screws to be removed with the attached screwdriver shaft andremoving the screws by engaging the screwdriver shaft with the screws tobe removed, and rotating the screwdriver shaft. The microelectroniccomponent is then removed.

If the microelectronic component has been removed after the screws hadbeen removed, then the screwdriver receiving tip is removed from theremoval tool, and a blade portion attached thereto. The removal tool isheated, thereby heating the blade portion. The heated blade portion isengaged against any residual, cured epoxy that remains on the substrateto remove the residual epoxy.

The microelectronic component can typically be bonded around the edgesthereof by a cured epoxy. It can include screws bonded by epoxy that aidin securing the microelectronic component to the substrate. In this typeof system, the screws are first removed, followed by removal of anyepoxy bonding the edges of the microelectronic component. The methodfurther comprises the steps of attaching a screwdriver receiving tip toa removal tool, wherein the screwdriver receiving tip includes anorifice for receiving a screwdriver shaft. The screwdriver shaft isreceived within the orifice so that it is freely rotatable therein. Theremoval tool is heated, thereby heating the screwdriver receiving tipand screwdriver shaft.

The screw to be removed is heated with the attached screwdriver shaft.The screw is removed by engaging the screwdriver shaft with the screwand rotating the screwdriver shaft. The screwdriver receiving tip andscrewdriver shaft are allowed to cool, and then removed. A blade portionis attached to the removal tool. The removal tool is heated, therebyheating the blade portion. The heated blade portion is positionedagainst the cured epoxy around the edge of the component and the epoxyremoved. The blade portion is then positioned between an edge of thecomponent and adjacent portion of the substrate to lift the componentfrom the substrate.

In still another aspect of the present invention, the epoxy is removedfrom the blade portion prior to the positioning step. The method furthercomprises the step of scraping off the epoxy from the substrate by theblade portion and removing the scraped epoxy by vacuum. The vacuum canbe applied by a vacuum wand, or the blade portion can include a vacuumchannel that connects to a source of vacuum.

In accordance with another aspect of the present invention, a removaltool is provided for removing a microelectronic component from asubstrate. The removal tool comprises a body having a proximal handleand a heating end, and a heating element positioned in the removal toolthat allows heating at the distal heating end.

A screwdriver receiving tip is removably mounted on the distal heatingend of the removal tool. The screwdriver receiving tip includes a distalend having an orifice. A screwdriver shaft is received through theorifice. The orifice and screwdriver shaft are dimensioned such that thescrewdriver shaft is freely rotatable within the orifice. A bladeportion is removably mounted to the removal tool after removal of thescrewdriver receiving tip. The heating element further comprises anelectric heating coil. The removal tool further comprises a distalthreaded receiving end, and the screwdriver receiving tip furthercomprises a proximal threaded annular attachment end that is screwedonto the threaded receiving end of the removal tool.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention willbecome apparent from the detailed description of the invention whichfollows, when considered in light of the accompanying drawings in which:

FIG. 1 is a perspective view of the removal tool having an attachedscrewdriver receiving tip and screwdriver shaft received through theorifice that engages a screw to be removed.

FIG. 2 is another perspective view showing the removal tool and attachedblade portion, and a vacuum wand that is manipulated to recover removedepoxy by vacuum.

FIG. 3 is still another perspective view showing the blade portion of aremoval tool positioned between the edge of the component and anadjacent portion of the substrate to lift the component from thesubstrate.

FIG. 4 is a partial perspective view showing the removal tool, bladeportion and a heating element in schematic.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likenumbers refer to like elements throughout.

The method of the present invention allows non-destructive removal of anepoxy bonded microelectronic component, such as an integrated circuitfrom a substrate. The invention is applicable also to staked fastenershaving screws, and allows localized heating of the cured epoxy withoutdamaging adjacent microelectronic components.

The present invention will first be described relative to a stakedfastener having screws that secure a microelectronic component to thesubstrate, as well as an epoxy bond around the edges thereof. Inaccordance with the present invention, the removal tool used in thepresent invention will also be described.

Referring now to FIG. 4, there is illustrated a removal tool inaccordance with the present invention. As illustrated, the removal tool10 includes a distal heating end 12a positioned on a cylindricalconfigured body 12. The heating end 12a includes external screw threads14 at the end to receive a mounting tool, such as a screwdriverreceiving tip 16 (FIG. 1), or a blade portion 18 (FIGS. 2-4). Theremoval tool 10 also includes a proximal end formed as a handle 20, andsecured to the cylindrical body 12 by a coupling 22. The handle 20includes therein a conventional heating element 24, connected to aheating coil 26 mounted in the body 12, such as typically found insoldering irons and other similar types of heating devices. The heatingelement 24 connects to a standard source of AC power to allow heating ofthe distal heating end 12a.

As shown in FIG. 1, a substrate 28, such as conventionally known tothose skilled in the art, includes a staked microelectronic component 30secured to the substrate by two screws 32 that have an epoxy bond, aswell an epoxy bond 34 around the edges of the staked microelectroniccomponent 30. It should be understood that the described tool and theremoval techniques to be described can be used for integrated circuitsand other microelectronic components as suggested by those skilled inthe art.

The screwdriver receiving tip 16 is removably mounted on the heating endof a removal tool as illustrated in FIG. 1. The screwdriver receivingtip 16 has an annular configured proximal end 36 that has internal screwthreads 38 to permit the screwdriver receiving tip to be screwed ontothe screw threads 14 at the distal heating end 12a of the removal tool10. The screwdriver receiving tip 16 is cylindrically configured andincludes a distal end 40 having an orifice 42 that receives ascrewdriver shaft 44. The screwdriver shaft 44 is dimensioned relativeto the orifice 42 so that the screwdriver shaft 44 is freely rotatablewithin the orifice 44. As illustrated, the screwdriver shaft 44 includesa connection end 46 that allows connection of the handle 48. Differentshafts can have different ends for engaging different size screws. Thesame handle can be used.

In accordance with the method of the present invention, the screwdriverreceiving tip 16 is attached to the removal tool 10 by screwing thescrewdriver receiving tip 16 onto the distal heating end 12a. The propersize screwdriver shaft with a desired end is then received within theorifice 42 of the screwdriver receiving tip. Typically, the distalheating end 12a and screwdriver receiving tip 16 has been heatedbeforehand to about 700 F. The amount of heat is controlled by controlknob 24a adjustment. Thus, when the screwdriver shaft 44 is receivedwithin the orifice, the already heated screwdriver receiving tip 16 willconduct heat into the screwdriver shaft 44. Once the screwdriver shaft44 is hot, the attached handle 48 is grasped by the operator, and theend of the screwdriver shaft placed on the screw 32 to be removed. Theepoxy surrounding the screw and the screw itself is heated. Thescrewdriver shaft is then rotated and the screw removed. This procedureis repeated for any other screws that secure the microelectroniccomponent to the substrate. The heat allows the epoxy bond to be brokenwithout causing excessive damage to the component and substrate.

Once the screws 32 have been removed, the removal tool 10 is allowed tocool sufficiently to allow the operator to remove the screwdriverreceiving tip 16 from the removal tool. A blade portion 18 (asillustrated in FIG. 4) is then screwed onto the distal heating end 12aof the removal tool 10. As illustrated, the blade portion 18 includes asupport body 50, which includes a ledge 52 for supporting a blade 54that is secured by an allen nut 56 or similar fastening means. Thus, itis possible to secure different size blades 54 onto the ledge 52depending on the type of epoxy to be removed, the thickness of the epoxylayer, and the type of microelectronic component that is secured by theepoxy onto the substrate. The support body includes an annular proximalend having internal threads 58 to engage the external threads 14 on thedistal heating end 12a of the removal tool.

Once the blade portion 18 has been screwed onto the removal tool 10, theremoval tool is heated to about 750 F., imparting heat onto the bladeportion and its mounted blade. As shown in FIG. 2, any excess epoxyaround the area where the microelectronic component was secured is thenscraped off. If the microelectronic component could not have beenremoved because of associated epoxy bond around the edges of thecomponent, then the epoxy is heated and scraped away from the componentedges. As shown in FIG. 2, a vacuum wand 60 is used to suck by vacuumthe scraped epoxy from the substrate. The vacuum wand is illustrated asa fine tube and can also, in certain embodiments, be attached to theremoval tool. However, in still another embodiment shown in FIG. 4, itis possible to form a vacuum channel 62 in the body of the bladeportion. A vacuum orifice 64 is formed at the distal end of the bladeportion and can be used to draw the vacuum and remove the epoxy. Avacuum inlet 66 can be formed on the blade portion and connected to avacuum tube or other source of vacuum.

In the case where the epoxy around the edges of the microelectroniccomponent has to be removed, the blade portion 18 can be positionedbetween the edge of the component and an adjacent portion of thesubstrate 28 to lift the component from the substrate, as illustrated inFIG. 3.

Once the microelectronic component has been lifted from the substrate,any excess epoxy can be heated by the blade portion and vacuum drawneither through a separate vacuum wand or within the blade portion, asshown in the illustrated blade portion of FIG. 4, where the vacuum isdrawn to a channel in the blade portion into the distal tip where thevacuum draw at the tip removes any epoxy that has been scraped.

It is evident that the present invention now allows removal ofmicroelectronic components, such as integrated circuits, from asubstrate, which are secured by an epoxy bond around the edges and onany fasteners, such as screws. The invention allows for non-destructiveremoval and is advantageous because the microelectronic components canbe used again.

It is also possible that the substrate can be used again, thus savingcosts.

Many modifications and other embodiments of the invention will come tothe mind of one skilled in the art having the benefit of the teachingspresented in the foregoing descriptions and the associated drawings.Therefore, it is to be understood that the invention is not to belimited to the specific embodiments disclosed, and that themodifications and embodiments are intended to be included within thescope of the dependent claims.

That which is claimed:
 1. A method for removing a microelectroniccomponent from a substrate, wherein the component is bonded around theedges thereof by a cured epoxy, the method comprising the stepsof:heating a removal tool comprising a blade portion; engaging theheated blade portion against cured epoxy positioned around the edge ofthe component and removing the epoxy; and thereafter positioning theblade portion between an edge of the component and an adjacent portionof the substrate to lift the component from the substrate.
 2. The methodaccording to claim 1, and further comprising the step of removing epoxyfrom the blade portion prior to the positioning step.
 3. The methodaccording to claim 1, and further comprising the step of scraping offthe epoxy from the substrate by the blade portion and removing thescraped epoxy by vacuum.
 4. The method according to claim 1, whereinsaid microelectronic component includes screws bonded by epoxy that aidin securing microelectronic the component to the substrate, and furthercomprising the steps of:attaching a screwdriver tip to the removal tool;heating a screw to be removed with the attached screwdriver tip; andturning the screwdriver tip after heating the screw for removal of thescrew thereof.
 5. The method according to claim 4, wherein thescrewdriver tip is freely rotatable relative to the removal tool.
 6. Themethod according to claim 1, and further comprising the step of heatingthe blade portion to about 750 F.
 7. A method for removing amicroelectronic component from a substrate, wherein the microelectroniccomponent includes screws bonded by epoxy that aid in securing themicroelectronic component to the substrate, and further comprising thesteps of:attaching a screwdriver receiving tip to a removal tool,wherein the screwdriver receiving tip includes an orifice for receivinga screwdriver shaft; receiving within the orifice a screwdriver shaftthat is freely rotatable therein; heating the removal tool and therebyheating the screwdriver receiving tip and screwdriver shaft; heating thescrews to be removed with the attached screwdriver shaft; removing thescrews by engaging the screwdriver shaft with the screws to be removedand rotating the screwdriver shaft; and removing the microelectroniccomponent.
 8. A method according to claim 7, and further comprising thesteps of heating the removal tool, screwdriver receiving tip, andscrewdriver shaft to about 700 F.
 9. A method according to claim 7, andfurther comprising the steps of:removing the screwdriver receiving tipand attaching to the removal tool a blade portion; heating the removaltool and thereby heating the blade portion; and engaging the heatedblade portion against any residual, cured epoxy that remains on thesubstrate and removing the residual epoxy.
 10. A method for removing amicroelectronic component from a substrate, wherein the microelectroniccomponent is bonded around the edges thereof by a cured epoxy, andincluding screws bonded by epoxy that aid in securing themicroelectronic component to the substrate, and further comprising thesteps of:attaching a screwdriver receiving tip to a removal tool,wherein the screwdriver receiving tip includes an orifice for receivinga screwdriver shaft; receiving within the orifice a screwdriver shaftthat is freely rotatable therein; heating the removal tool and therebyheating the screwdriver receiving tip and screwdriver shaft; heating thescrew to be removed with the attached screwdriver shaft; removing thescrew by engaging the screwdriver shaft with the screw to be removed androtating the screwdriver shaft; removing the screwdriver receiving tipand screwdriver shaft and attaching to the removal tool a blade portion;heating the removal tool and thereby heating the blade portion; engagingthe heated blade portion against cured epoxy around the edge of thecomponent and removing the epoxy; and positioning the blade portionbetween an edge of the component and an adjacent portion of thesubstrate to lift the component from the substrate.
 11. The methodaccording to claim 10, and further comprising the step of removing epoxyfrom the blade portion prior to the positioning step.
 12. The methodaccording to claim 10, and further comprising the step of scraping offthe epoxy from the substrate by the blade portion and removing thescraped epoxy by vacuum.
 13. The method according to claim 10, andfurther comprising the step of heating the blade portion to about 750 F.